It is common to cut sheet metal into pieces that are bent or otherwise assembled to form ductwork. A conventional computer numeric controlled (CNC) cutting apparatus for carrying out such cutting includes a horizontal support table for supporting sheet metal to be cut, a longitudinally movable gantry positioned above the table, a transversely movable carriage mounted on the gantry, and a single cutter carried by the carriage. The gantry and carriage are moved while the cutter is operated so that sheet metal is cut according to predetermined patterns. For example, an apparatus of the above-described type is disclosed in U.S. Pat. No. 4,554,635.
It is common for sheets of thermal insulation, such as insulation that is constructed of fiber glass, wood pulp, or the like, to be cut into pieces that are applied to the ductwork that is manufactured as described above. For example, it is conventional for the cutter of an apparatus of the above-described type to be a gas torch, and for the torch to be used to cut both the sheet metal and the insulation. That is, the insulation is cut with a flame from the gas torch. Cutting insulation with the flame of a gas torch can be very disadvantageous because insulation is often flammable, and numerous fumes are released.
It is also conventional to cut the insulation with a cutter that is separate from the cutting apparatus used to cut the sheet metal. As one example, the cutter used to cut the insulation can be a manually operated cutter, such as hand shears. Using a manually operated cutter can be disadvantageously labor intensive, and does not produce repeatable parts. It has also been conventional for the insulation to be cut with a water jet cutter of a CNC cutting apparatus, such that a first CNC cutting apparatus with a torch is used to cut the sheet metal, and a completely separate CNC cutting apparatus with a water jet cutter is used to cut the insulation. Purchasing, operating and maintaining two separate CNC cutting apparatus for cutting sheet metal and insulation can be cost prohibitive. In addition, operating the two separate cutting apparatus can be particularly inefficient when it precludes capitalizing upon similarities between the patterns defining how the sheet metal and insulation are cut.
U.S. Pat. No. 5,635,086 to Warren, Jr. et al. discloses a computer-controlled cutting apparatus having a horizontal support table for supporting metal to be cut, a longitudinally movable gantry positioned above the table, and a transversely movable carriage mounted on the gantry. The carriage has both a laser cutting head and a plasma arc cutting head mounted thereto, but both of the cutting heads are described as being used to cut metal. Although it is disclosed that the gantry could be selectively movable over dual or triple tables which are positioned in tandem, it is not disclosed that the tandem tables can be of different types. Even though the Warren, Jr. et al. patent discloses two different types of cutting heads mounted on the same carriage, there is a teaching away from using both a water-jet cutter and a plasma arc cutter together, because the water from the water-jet cutter could interfere with the operation of a downdraft system associated with the plasma arc cutter. In addition, the Warren, Jr. et al. patent does not disclose that the two cutting heads carried by the same carriage are used to cut completely different types of material.
Accordingly, there is a need for an improved cutting apparatus, such as for cutting sheet metal and insulation, and the like.